Stopper



FIG. 1 is a side elevational view of a stopper showing my new design, the opposite side being a mirror image thereof;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof; and

FIG. 4 is an enlarged detail sectional view taken along line 4--4 of FIG. 2. 

The ornamental design for a stopper, substantially as shown and described. 